Silicon Labs' highly integrated SiM3U1xx MCUs are well suited for
digital Class D power amplification applications without the hassle and
expense of adding discrete Class D amplifiers. The SiM3U1xx MCUs include
a 300 mA high-drive I/O capable of directly driving a small speaker, a
crystal-less USB transceiver compatible with the USB audio interface,
two 250 ksps 12-bit analog-to-digital converters (ADCs), and an I2S
receiver that supports audio streaming from a PC, a portable music
player or a wide range of I2S-enabled audio devices. The only external
components required to drive Class D audio from SiM3U1xx MCUs are
inexpensive inductors, some capacitors and ferrite beads.

In addition to supporting Class D audio capabilities, the new ToolStick
also enables developers to add capacitive touch buttons and sliders to
their 32-bit embedded systems or use the SiM3U1xx MCU's high-drive I/Os
with pulse-width modulation (PWM) to directly drive other components
such as small motors, eliminating the need for separate power
field-effect transistors (FETs).

The Class D ToolStick board is powered from USB using the SiM3U1xx MCU's
internal 5 V regulator, and it can play music from a stereo jack, a
computer or a recorded message using a simple speaker. The Class D
ToolStick provides four modes of operation: sampling data from a
portable music player using the MCU's on-chip ADCs, USB audio streaming
from a PC, playing pre-recorded sound clips stored from on-chip flash
memory using a common audio compression algorithm, and a voice recorder
that stores data in flash usng an audio compression algorithm.
Developers can easily handle mode transition through capacitive touch
buttons and control volume with a capacitive touch slider.

The Class D ToolStick evaluation kit comes complete with hardware Gerber
files and software to streamline the process of adding Class D audio to
embedded applications. In addition, the ToolStick can serve as a
cost-effective, general-purpose development platform for Precision32
MCUs. It features a built-in USB-based debugger/programming interface
and accessible pins for easy prototyping. The Class D ToolStick debug
interface is fully operational with Silicon Labs' complimentary
Precision32 IDE, compiler and AppBuilder crossbar configuration
software, as well as Keil tool chains.

The Class D ToolStick evaluation kit is available now and priced at $35
(USD MSRP). The kit includes full source code and implements a Class D
amplifier demonstration using a small-footprint 40-pin 6 mm x 6 mm
package SiM3U1xx MCU.

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high-performance, analog-intensive, mixed-signal ICs. Developed by a
world-class engineering team with unsurpassed expertise in mixed-signal
design, Silicon Labs' diverse portfolio of patented semiconductor
solutions offers customers significant advantages in performance, size
and power consumption. For more information about Silicon Labs, please
visit www.silabs.com.

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